This invention relates to DC-to-DC power converters of the zero-current switching type.
In some such converters (for example the single-ended forward zero-current switching converters of the kind disclosed in Vinciarelli, U.S. Pat. No. 4,415,959, incorporated herein by reference, or series-resonant converters, or other resonant converters), power from a DC source is converted by way of a series of quantized energy transfer cycles into power for delivery to a load. Each energy transfer cycle has a period governed by the time constant of a coupled effective inductance (L) and capacitance (C) in the circuit. A switching device is connected in series with the source. The switching device is switched on and off (at times of essentially zero current) by a controller involving a feedback loop which senses the voltage across the load. The feedback loop spaces the energy transfer cycles at such time intervals that the voltage across the load is kept at a desired level. The power rating of the converter depends on the values of L and C. Such converters typically provide up to 200 watts of power.
One approach to delivering more power is simply to scale up the electrical components.
Another approach is to operate an array of converter modules in parallel, but independently. Some of the mo dules in the array will then typically saturate, while others make up any shortfall in power needed by the load.
In a third approach, converters within the array are forced to share power but without having to switch coherently at the same frequency. Such incoherent master-slaves configurations lead to beat frequencies.